I found this article very interesting and thought I would post the link here.
Quote:
an association has recently been established between aberrant behavior and thyroid dysfunction in the dog, and has been noticed in cats with hyperthyroidism. Typical clinical signs include unprovoked aggression towards other animals and/or people, sudden onset of seizure disorder in adulthood, disorientation, moodiness, erratic temperament, periods of hyperactivity, hypoattentiveness, depression, fearfulness and phobias, anxiety, submissiveness, passivity, compulsiveness, and irritability.
Thyroid dysfunction was found in 62% of the aggressive dogs, 77% of seizuring dogs, 47% of fearful dogs, and 31% of hyperactive dogs.The article also looks at the evidence against vaccines and medicines as causes for behavioral issues.
